The PSD follows a \(1/f\)  dependence which, extrapolated at \({1}{Hz}\) , gives \({23}{eV^2/Hz}\) .
In term of qubit energy fluctuations, the obtained value is relatively large if we consider the operation of the qubit in a spin-valley mode.
In this mode, the spin-valley mixing is exploited to drive coherent oscillations through electric dipole spin resonance next to the hotspot [1]}.
Fluctuations of the valley splitting translate into fluctuations of the Larmor frequency \(h\delta f = 1/2\delta E_{VS}\)  at the hotspot[2]}.
It corresponds to a fluctuation in the spin precession of about \({0.6}{GHz}/\sqrt{Hz}\) , which is faster than the decoherence rate due to the hyperfine fluctuations in natural silicon, and is on the order of the decoherence rate of charge and valley qubits [3]}, [4]}. This could prove detrimental for EDSR exploiting the spin-valley mode, limiting the coherence time when the spin-valley coupling is turned on [5]}, [6]}.
It may therefore be necessary to operate further away from the hotspot to avoid fast decoherence, at the cost of slower Rabi frequency or to lower the confinement potential to reduce the valley splitting sensitivity to electric field [1]}.
